WM8310CGEBSLASHV datasheet(104/291 Pages) WOLFSON

104 / 291 page

WM8310

Pre-Production

PP, May 2012, Rev 3.1

104

17 POWER SUPPLY CONTROL

17.1 GENERAL DESCRIPTION

The WM8310 can take its power supply from a Wall adaptor, a USB interface or from a single-cell

lithium battery. The WM8310 autonomously chooses the most appropriate power source available,

and supports hot-swapping between sources (ie. the system can remain in operation while different

sources are connected and disconnected).

Comparators within the WM8310 identify which power supplies are available and select the power

source in the following order of preference:



Wall adaptor (WALLVDD)



USB power rail (USBVDD)



Battery (BATTVDD)

Note that the Wall supply is normally the first choice of supply, provided that it is within the operating

limits quoted in Section 6. The WM8310 can operate with any combination of these power supplies,

or with just a single supply.

When WALLVDD or USBVDD is selected as the power source, this may be used to charge the

Battery, using the integrated battery charger circuit.

The recommended connections between the WM8310 and the WALL, USB and Battery supplies are

illustrated in Figure 24. Note that the external FET components may be omitted in some applications;

as described later in this section.

Figure 24 WM8310 Power Supply Connections

SYSVDD is primarily an output from the WM8310; this output is the preferred supply, where the

WM8310 has arbitrated between the Wall, Battery and USB connections. This output is suitable for

supplying power to the other blocks of the WM8310, including the DC-DC Converters and LDO

Regulators. SYSVDD is also an input under some conditions, such as battery charging from the Wall

supply. The voltage at the SYSVDD load connection point is sensed using the SYSVMON pin.

All loads connected to the WM8310 should be connected to the SYSVDD pin. The inputs to the DC-

DC Converters and LDOs are typically connected to the SYSVDD pin. The inputs to the LDOs may,

alternatively, be connected to the outputs of the DC-DCs if desired.

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